Measurement is the basis for assessing potential improvements in healthcare quality. Measures may be classified into four categories: volume, structure, outcome, and process (VSOP). Measures of each type should be used with a full understanding of their cost and benefit. Although volume and structure measures are easily collected, impact on healthcare results is not always clear. Process measures are generally more difficult and expensive to collect, and the relationship between process and outcomes is only recently being explored. Knowledge of measure types and relationships among them, as well as emerging evidence on the role of patient satisfaction, must be used to guide improvements and ultimately for demonstrating value in healthcare.